This is a known issue. This can potentially happen if you have a newer version of the database server than the ADO.NET provider.

Specifically, CR #742355 is implemented on the database server (the server is a higher build than 12.0.1.3924 or 16.0.0.1588), but CR #741707 is not implemented on the ADO.NET provider (the ADO.NET provider is a lower version than 12.0.1.3924 or 16.0.0.1588).

Deploying the same version of the ADO.NET provider to match the database server version (e.g. 12.0.1.3942) to the client should resolve this issue.

I had the same exception with EF6, Server 12.0.1.4165, Ado.NET Provider 12.0.1.41654 ?, but in my case it was caused by different threads accessing the same db context which of course is not supported. The scenario can easily be reproduced by starting several threads accessing the same context.